The various kinds of persons, animals and objects which cause impurity by touch or other means need to be listed and discussed. In particular, the question must be asked whether any pattern or basic theme can be discovered in all these varied causes of impurity.

In Judaism, the human corpse is by far the greatest source of impurity, in the sense that it causes the most severe level of impurity, and also contaminates in the greatest variety of modes. This very fact raises the possibility that death is the basic theme for which we are looking. Can it be that every source of impurity functions as a form of death? This has been argued by many scholars, and is supported by the fact that even animals in the Jewish system cause impurity only when they are dead. The theory, however, faces difficulties: in what way, for example, does the impurity caused by emission of semen, or by menstruation, or by childbirth, link with the concept of death?

In societal terms, the supreme impurity of the human corpse has some interesting consequences. It means, for example, that Judaism does not share with Christian societies the practice of interring the corpses of saints or other prominent people in shrines or other places of worship. For in death, all are equal: the corpses of saints are just as much sources of ritual impurity as those of other humans, and the essence of the Jewish system is that ritual impurity should be excluded from the Temple. In the holiest shrine in Christendom, the body of Saint Peter is allegedly buried.